252 RESEARCHES ON FUNGI 



by Oort ; for, if it had been, the spores produced from the test-tube 

 fruit-body should have fallen into two groups only, i.e. (Ab) and 

 (AB) or (^6) and (ab), and not into four groups (AB), {ab), (Ab), 

 and (aB), plus an extra exceptional group represented by the spore 

 which produced myceUum No. 6. 



The analysis given in Table VI may possibly be explained as 

 follows. Somehow or other, as a result of placing the diploid 

 inoculum {AB)-]-{ab) in contact with the haploid mycelium (^6), 

 a nucleus (aB) came into existence and thus, after division, provided 

 mates for the (^6) nuclei in the (^6) mycelium. Did a nucleus 

 (AB) or a nucleus (ab) of the inoculum alter one of its factors so as 

 to become a nucleus (aB) ? Or, to meet the emergency when the 

 haploid and diploid myceUa fused, did the {AB) and {ab) nuclei of 

 some conjugate pair in the diploid mycelium fuse together and the 

 fusion nucleus then undergo a reduction division or reduction 

 divisions to produce the four types of nuclei {AB), {ab), {Ab) and 

 {aB) so that a nucleus {aB) could pass into the large haploid 

 mycehum {Ab) ? 



As bearing on the answer which may be given to the questions 

 just raised, the following remarks may be made. Nuclear fusion 

 and reduction in a diploid mycelium seems, a priori, a rather unlikely 

 phenomenon as, hitherto, in the Hymenomycetes, these processes 

 have been found to occur only in the basidia. Furthermore, if, in 

 the particular case under discussion, a nucleus {aB) had been pro- 

 duced by nuclear fusion and nuclear reduction in one of the hyphae 

 of the diploid mycelium, there seems no reason why such a nucleus 

 should not, on entering the large (^6) mycelium, have behaved 

 like other {aB) nuclei, e.g. those in Experiment No. 7 of Table V, 

 and have brought about a complete, instead of only a partial, 

 diploidisation of the {Ab) mycelium. The fact that the {Ab) 

 mycehum became diploidised only one-half the way around its 

 periphery suggests that the {aB) nuclei were not iully compatible 

 with the (^6) nuclei. Finally, the solution of the problem in hand 

 must await further analysis of the clamp-connexion-bearing myceha 

 produced in a new series of illegitimate combinations of the type 

 (^6) X {AB)-\-{ab). Up to the present, the writer has not been 

 able to undertake the work suggested. 



